Bezier Curves

I want to migrate my project from Silverlight 3 to Silverlight 4. Everything is going good except drawing of Bezier curve on top of my Deep Earth map control. In Silverlight 3 I've created custom layer that inherits geometry layer. In my custom layer I managed
to draw Bezier curve by overriding method UpdatePathData. But in Deep Earth for Silverlight 4 I just can get this thing to work. Is there any way to get a Bezier curve on top of Deep Earth map control?